PC-MOS/386 was another multi-user MS-DOS Operating system. And they had some great ads, like above.

I was able to track down a few disks but of them all only the version 5 one seemed to run to some degree under Qemu. Or at least the $386.sys memory driver.

pc-mos 1.02

This is about as much as I got out of PC-MOS/386 1.0

pc-mos 3.00

While PC-MOS/386 3.0 loads, if you try to load the protected mode $386.sys driver it just hangs.

pc-mos 5.01

And PC-MOS/386 5.0 not only loads, but will load up with the protected mode driver on Qemu.

pc-mos 5.01 protected mode

I’ve managed to get a serial ‘terminal’ to run, and for anyone who ever needs the hint, here is the config.sys, autoexec.bat and user01.bat file to make it boot up…. Neither VirtualPC, nor VMWare can boot up with the drivers.

So what is it like? Under emulation lots of keystrokes are lost, and it feels slow. I’m sure it’s a COMPLETELY different story on actual hardware. PC-MOS 5.0 also cannot run DPMI programs, which is a shame. Then again DPMI was a ‘new and exciting’ thing in 1992 so I guess it’s not that surprising. I’m not aware of any support to run Windows 3.1 but again 1992 was when the tide really started to turn to Windows.

As they mention on wiki memory costs, and slow disks of the time certainly made things like PC-MOS really slow.

What is interesting is that these versions include a CP/M 8086 emulator. I would imagine that would be a ‘big deal’ for users of the older MP/M to migrate into a newer 80386 environment. From what I’ve seen in other places these were compatible with MS-DOS 3.0 . It can also read extended dos partitions! Since they predate VCPI/DPMI there is no way to run protected mode applications. Concurrent DOS/386 is later followed up with Digital Research Multiuser DOS. It is interesting, well to me that DR-DOS was basically a single user, single tasking version of the Multiuser DOS.

Multiuser DR-DOS

I was able to install this on Qemu 0.13.0. Although this includes some IPX/SPX stuff from the later purchase of Digital Research by Novell, it still remains a largely MS-DOS 3.3 compatible OS. Because it uses protected mode, and the v86 mode, it is still incapable of running VCPI/DPMI programs. Also absent is the CP/M emulator. I think there was a DR-DOS 6 equivalence sold as a multiuser, but by the time of DR-DOS 7, the product had been forked and several VARS started to sell their own versions based on Multiuser DR-DOS. These included (but probably not a complete list)

REAL/32 certainly feels a lot like DR-DOS (which it is derived from) and what is cool is that it supports DPMI applications. I’ve tested some Borland Pascal stuff, along with DJGPP. Like the others it supports serial terminals to be hooked up.

real32 serial connection

Qemu makes it super easy to simple to switch to the serial port, and bring up the ‘second user’. I’m pretty sure you could use qemu to redirect it’s serial port over TCP…

And speaking of networking, the install program also seems to have some kind of networking config built in, so I would imagine each VM can have it’s own IPX/SPX setup? I’ll have to mess some more with it.

This has been a fun thing to go through, but at one point it was a popular trend to convert big expensive 386 computers from the late 1980’s into multi-user, multi-tasking beasts much like a mainframe. But instead of CICS, and PROFS people ran Dbase III, WordPerfect, and all kinds of email solutions from ccmail, to MS mail, and even some dbase programs, compiled by clipper into being email clients.

In a way things were more ‘simple’ back then, and the 80386 CPU had a card up it’s sleeve v86 mode. v86 mode provides hardware emulation of a 8086, allowing the base OS to spawn dozens of these virtual machines. All that was up to the ‘supervisor’ was to create virtual peripherals, much like how Windows/386 of the day ran multiple MS-DOS VM’s on a single machine that you could see at once, these solutions provide the output to multiple terminals.

While Windows/386 sat on top of MS-DOS, these multitasking DOS’s had the v86 mode multitasking as part of it’s core, and some of the later ones were themselves protected mode operating systems.

But juggling multiple MS-DOS applications at one could be quite a challenge. And of course there was the whole dos extender thing, leading up to VCPI, and DPMI.

While MP/M-86 is a grand daddy to a bunch of Digital Research derived OS’s, it’s not 386 specific so I’m going to omit it for now. I’m sure it’ll be worth doing it’s own write up.

I’m sure I’m going to miss a bunch of these, but let’s have a quick rundown.

Concurrent DOS/386

DR-Multiuser-DOS 5.0

Real/32

TSX-32

PC-MOS/386

VM/386

VMOS/3

If anyone knows of any others feel free to give me a shout. It does seem that multiuser DOS was a good market at one point.